Dudenredaktion; Kleiner, Stefan; Knöbl, Ralf (2015) [First published 1962], Das Aussprachewörterbuch (in German) (7th ed.), Berlin: Dudenverlag, p. 590, ISBN978-3-411-04067-4. According to this source, the pronunciation with [eː] is mainly found in Northern Germany (so Mecklenburg-Vorpommern itself as well). It is the historical pronunciation. In other regions, the spelling pronunciation with [ɛ] is usual.